Luis ate 3 slices of pie. Ishaan ate 2 slices. If there were initially 9 slices, what fraction of the pie is remaining?
$\text{fraction of pie eaten} = \dfrac{\text{number of slices remaining}}{\text{number of slices total}}$ Together they ate 5 slices, which leaves 4 out of 9 slices remaining. There is $\dfrac{4}{9}$ of the pie remaining.